High-Speed Imaging of a Laser Ablation Process Using Parallel Phase-Shifting Interferometry

Laser-ablated plumes were characterized using a high-speed, parallel, phase-shifting interferometry to clarify influence of an expanding plume on a subsequent pulse irradiation at a high-repetition rate process. After the pulsed-laser irradiation on the surface of the work piece, the ablated material rapidly expands from the processing point. The main issue in this paper is the influence of the ejected material on the subsequent pulse incidence. To evaluate the influence of the material ejected from the work piece in an ultrashort pulse laser process, we successfully visualized the shape and characteristics of the material using a high-speed, parallel, phase-shifting interferometry. They offer a large amount of information than that in self-emission images only and could provide quantitative values, such as spatial distributions of the ejected material. Through these measurements, the effect of the ejected material on the processing result was confirmed.